sbin/fsck_msdosfs/boot.c

48 	u_char block[DOSBOOTBLOCKSIZE];
52 	if ((size_t)read(dosfs, block, sizeof block) != sizeof block) {
53 		perr("could not read boot block");
57 	if (block[510] != 0x55 || block[511] != 0xaa) {
58 		pfatal("Invalid signature in boot block: %02x%02x",
59 		    block[511], block[510]);
69 	boot->bpbBytesPerSec = block[11] + (block[12] << 8);
78 	boot->bpbSecPerClust = block[13];
85 	boot->bpbResSectors = block[14] + (block[15] << 8);
93 	boot->bpbFATs = block[16];
100 	boot->bpbRootDirEnts = block[17] + (block[18] << 8);
107 	boot->bpbSectors = block[19] + (block[20] << 8);
115 	boot->bpbMedia = block[21];
118 	boot->bpbFATsmall = block[22] + (block[23] << 8);
126 	boot->SecPerTrack = block[24] + (block[25] << 8);
127 	boot->bpbHeads = block[26] + (block[27] << 8);
130 	boot->bpbHiddenSecs = block[28] + (block[29] << 8) +
131 	    (block[30] << 16) + (block[31] << 24);
134 	boot->bpbHugeSectors = block[32] + (block[33] << 8) +
135 	    (block[34] << 16) + (block[35] << 24);
155 		if (!memcmp(&block[3], "EXFAT   ", 8)) {
161 		boot->FATsecs = block[36] + (block[37] << 8)
162 				+ (block[38] << 16) + (block[39] << 24);
164 		if (block[40] & 0x80)
165 			boot->ValidFat = block[40] & 0x0f;
168 		if (block[42] || block[43]) {
170 			       block[43], block[42]);
179 		boot->bpbRootClust = block[44] + (block[45] << 8)
180 			       + (block[46] << 16) + (block[47] << 24);
183 		boot->bpbFSInfo = block[48] + (block[49] << 8);
185 		/* Sector number of the backup boot block, ignored */
186 		boot->bpbBackup = block[50] + (block[51] << 8);
199 		/* Read in and verify the FSInfo block */
203 			perr("could not read fsinfo block");
216 			pwarn("Invalid signature in fsinfo block\n");
238 			/* We appear to have a valid FSInfo block, decode */
344 		perr("could not read fsinfo block");
366 	 * support for FAT32) doesn't maintain the FSINFO block
369 	 * Therefore, we handle the FSINFO block only informally,